• Structural Engineering and Mechanics
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• 제46권3호
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• pp.433-445
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• 2013

Vibration-based structural identification has become an important tool for structural health monitoring and safety evaluation. However, various kinds of uncertainties (e.g., observation noise) involved in the field test data obstruct automation system identification for accurate and fast structural safety evaluation. A practical way including a data preprocessing procedure and a vector backward auto-regressive (VBAR) method has been investigated for practical bridge identification. The data preprocessing procedure serves to improve the data quality, which consists of multi-level uncertainty mitigation techniques. The VBAR method provides a determinative way to automatically distinguish structural modes from extraneous modes arising from uncertainty. Ambient test data of a cantilever beam is investigated to demonstrate how the proposed method automatically interprets vibration data for structural modal estimation. Especially, structural identification of a truss bridge using field test data is also performed to study the effectiveness of the proposed method for real bridge identification.

• 한국산업융합학회 논문집
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• 제26권6_3호
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• pp.1279-1288
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• 2023

Recently, domestic leisure boats have been actively researching eco-friendly product development to enter the global market. Since the hulls of existing leisure boats are mainly made of fiber reinforced plastic (FRP) or aluminum, design techniques for securing structural safety by applying related materials have been mainly studied. In this study, an initial structural design safety assessment of a trimaran pontoon leisure boat with a modular hull structure and eco-friendly high-density polyethylene (HDPE) material was conducted, and sensitivity evaluation and optimization analysis for lightweight design were performed. The initial structural design safety assessment was carried out by creating a finite element analysis model and applying the loading conditions specified in the ship classification regulation to check whether the specified allowable stresses are satisfied. For the sensitivity evaluation, the influence of stress and weight of each hull structural member was evaluated using the orthogonal array design of experiments method, and an approximate model based on the response surface method was generated using the results of the design of experiments. The optimization analysis set the thickness of the hull structural members as the design variable and considered the optimal design formulation to minimize the weight while satisfying the allowable stress. The algorithm of the optimization analysis applied the Gradient-population Based Optimizer (GBO) to improve the accuracy of the optimal solution convergence while reducing the numerical cost. Through this study, the optimal design of a newly developed eco-friendly trimaran pontoon leisure boat with a weight reduction of 10% was presented.

• 한국전산구조공학회논문집
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• 제29권1호
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• pp.1-8
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• 2016

본 논문에서는 원심식 대형 압축기 구동용 모터 베이스 프레임의 구조해석 및 콘크리트 타설에 따른 구조안전성 평가를 수행하였다. 먼저 모터 베이스 프레임에 적용되는 네 가지 하중조건에 따른 구조해석을 진행하고 최대 비틀림 에너지 이론 및 Mohr-Coulomb 이론을 통하여 구조안전성을 평가하였다. 구조해석 결과에서 취약한 구조안전성을 나타낸 연결부 등의 불연속적인 부분에서 발생하는 국부응력에 대하여 ASME VIII Div. 2에 따른 구조안전성 평가를 적용함으로써 좀 더 합리적으로 구조안전성 평가를 수행할 수 있었다. 또한, 모터 베이스 프레임 내부에 콘크리트 타설 및 미타설에 따른 구조해석 및 ASME 구조안전성 평가를 통하여 모터 베이스 프레임의 구조안전성을 정량적으로 비교하여 콘크리트 타설로 인한 구조 안전성의 향상을 확인하였다.

• 대한안전경영과학회지
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• 제23권4호
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• pp.67-72
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• 2021

To ensure the safety and functionality of a railroad bridge, maintaining the integrity of the bridge via continuous structural health monitoring is important. However, most structural integrity monitoring methods proposed to date are based on modal responses which require the extracting process and have limited availability. In this paper, the applicability of the existing damage identification method based on free-vibration reponses to time-domain deflection shapes due to moving train load is investigated. Since the proposed method directly utilizes the time-domain responses of the structure due to the moving vehicles, the extracting process for modal responses can be avoided, and the applicability of structural health evaluation can be enhanced. The feasibility of the presented method is verified via a numerical example of a simple plate girder bridge.

• 한국구조물진단유지관리공학회 논문집
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• 제25권3호
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• pp.85-91
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• 2021

건축시설물 중 제1종 시설물과 제2종 시설물은 유지관리를 위해 정기적으로 정밀안전점검과 정밀안전진단을 실시한다. 건축물의 점검 및 진단을 실시하는 경우 상태평가, 기울기 및 침하, 안전성평가를 종합하여 건축물의 등급이 결정된다. 그리고 평가등급은 점검 및 진단의 주기를 결정한다. 평가 등급이 좋지 않다면 점검 및 진단 주기는 짧아지고, 이로 인한 유지관리 비용은 증가하게 된다. 따라서 건축물을 평가하는 방법은 명확하여야 한다. 상태평가는 부재단위 평가, 층단위 평가, 종합 평가로 이루어진다. 이 중 부재단위 평가는 현장조사와 시험 결과를 통해 등급을 판정한다. 본 연구에서는 상태평가의 첫 번째 단계인 부재단위 평가에 대해 평가방법과 평가기준을 분석하여 개선점을 도출하였으며, 이를 개선하여 현재 부재의 상태점수를 반영할 수 있는 함수식을 제시하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.29-32
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• 2006

Different from new or reconstruction of an apartment housing, the structural safety in the remodelling construction can be obtained through the repair and strengthening process based on the safety diagnosis and evaluation of structural performance. In this study, structural performance of existing members such as, reinforced concrete slabs, beams and columns are investigated through experimental tests. The structural members were obtained from the existing apartment housing which will be demolished. Test results showed that most specimens have a sufficient structural capacity except for some special case, for example, specimens with severe cracks or concrete loss due to improper casting. This same severe deteriorated or defective structure members originated from bad concrete casting or careless construction process should be repaired and strengthened before an remodelling construction.

• 산업경영시스템학회지
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• 제41권4호
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• pp.213-219
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• 2018

Mechanical components are to be produced with accurate dimensions in order to function properly in assemblies of a machine. Once designs of mechanical components are created, designers examine the designs by adopting many known experimental methods. A primary test method includes stress and strain evaluation of structural parts. In addition, fatigue test and vibration analysis are an important test method for mechanical components. Real experiments at a laboratory are established when products are manufactured. Since design changes should be done before producing the designs in factories, rapid modifications for new designs are required in production industries. FEM simulation is a proper choice for a design evaluation with speed at a detail stage in design process. This research focuses modeling and mechanical simulation of a mechanical component in order to ensure structural safety. In this paper, a universal joint, being used in driving axels of vehicles, is studied as a target component. A design model is created and tested in some ways by using commercial software of FEM. The designed component is being twisted to transmit heavy power and thus, torsional stress should be under strengths of the component's material. The next is fatigue analysis to convince fatigue cycles to be within the endurance limit of the material. Another test is a vibration analysis for rotational components. This research draws final conclusions from these test analyses and recommends whether the designed model is under safety condition in terms of mechanical structure.

• Geomechanics and Engineering
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• 제19권3호
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• pp.283-293
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• 2019

Evaluating the stability of the excavation face of the cross-river shield tunnel with good accuracy is considered as a nonlinear and multivariable complex issue. Understanding the stability evaluation method of the shield tunnel excavation face is vital to operate and control the shield machine during shield tunneling. Considering the instability mechanism of the excavation face of the cross-river shield and the characteristics of this engineering, seven evaluation indexes of the stability of the excavation face were selected, i.e., the over-span ratio, buried depth of the tunnel, groundwater condition, soil permeability, internal friction angle, soil cohesion and advancing speed. The weight of each evaluation index was obtained by using the analytic hierarchy process and the entropy weight method. The evaluation model of the cross-river shield construction excavation face stability is established based on the idea point method. The feasibility of the evaluation model was verified by the engineering application in a cross-river shield tunnel project in China. Results obtained via the evaluation model are in good agreement with the actual construction situation. The proposed evaluation method is demonstrated as a promising and innovative method for the stability evaluation and safety construction of the cross-river shield tunnel engineerings.

• KIEAE Journal
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• 제12권2호
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• pp.33-38
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• 2012

This study aims to evaluate the structural safety of the balcony photovoltaic systems easily installed or moved on the buildings. Also, the systems are controlled by solar altitudes focused on its mobility rather than high efficiency generation performance thereof. The results of the study are as follows. Two types of typical photovoltaic systems which can be mounted on the balcony are proposed, and, the sizes of the systems are designed to be adjusted within certain ranges of the frames in order to attach the various rail sizes. To evaluate the structural safety of the proposed systems, several simulation evaluations are performed on the safety evaluation standards by the Ministry of Construction-Transportation and KCI 2007. The results are that the proposed plans are reasonable in terms of stress and deflection in the structural aspects at the wind pressures of $1,907(N/m^2)$ of external wall surface under the condition of wind velocity higher than 25(m/s).

• 전산구조공학
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• 제23권3호
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• pp.34-42
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• 2010